Progress toward chemical accuracy in the computer simulation of condensed phase reactions.

Bash, Paul A.; Ho, Lap; MacKerell, Alexander D.; Levine, David; Hallstrom, Philip

doi:10.1073/pnas.93.8.3698

Cited by 96 publications

(86 citation statements)

References 10 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The representation described in this paper may pro-vide a foundation for an efficient treatment of electronic structure that would compete with Gaussian basis set methods in applications for which chemical accuracy [35] is required. With this goal in mind, several easy-toimplement elaborations that would improve its performance are conceivable.…”

Section: Discussionmentioning

confidence: 99%

“…At this medium resolution, it seems that double-zeta quality transition energies are obtained; stepping up to the finest resolution produces improvements of less than 0.1eV for the lower cation ionization potential, and improvements slightly greater for the higher I.P. This accuracy of 0.1eV is unsatisfactory for many applications involving ground-state Born-Oppenheimer dynamics; the standard called for there, "chemical accuracy," is one kilocalorie per mole [35], which is approximately 43meV. Examining the lowest-resolution results, one can see that errors introduced going from the resolution of approximately ∆ = 0.3a 0 to 0.6a 0 are a substantial fraction of an electron volt.…”

Section: G Cubane (C8h8) Ionization Potentialmentioning

confidence: 99%

“…Using the values of b i from this fit, we obtain the value at which the accuracy of the computed ioniza- tion potentials for cubane is one kilocalorie per mole or 43meV, also known as "chemical accuracy" [35]. By solving 0.043 = b i ∆ 1.205 , in electronvolts, for ∆, given the fitted b i , we obtain ∆ = 0.139a 0 from both the I.P.…”

Section: G Cubane (C8h8) Ionization Potentialmentioning

confidence: 99%

“…We present the method in the next section, then results, and finally in the conclusion we speculate about possible elaborations to the method that could make it more versatile for excited state and time-dependent problems, and perhaps even competitive with Gaussian basis sets for the computation of results requiring chemical accuracy [35].…”

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

An efficient basis set representation for calculating electrons in molecules

et al. 2016

View full text Add to dashboard Cite

The method of McCurdy, Baertschy, and Rescigno, J. Phys. B, 37, R137 (2004) is generalized to obtain a straightforward, surprisingly accurate, and scalable numerical representation for calculating the electronic wave functions of molecules. It uses a basis set of product sinc functions arrayed on a Cartesian grid, and yields 1 kcal/mol precision for valence transition energies with a grid resolution of approximately 0.1 bohr. The Coulomb matrix elements are replaced with matrix elements obtained from the kinetic energy operator. A resolution-of-the-identity approximation renders the primitive one-and two-electron matrix elements diagonal; in other words, the Coulomb operator is local with respect to the grid indices. The calculation of contracted two-electron matrix elements among orbitals requires only O(N log(N )) multiplication operations, not O(N 4 ), where N is the number of basis functions; N = n 3 on cubic grids. The representation not only is numerically expedient, but also produces energies and properties superior to those calculated variationally. Absolute energies, absorption cross sections, transition energies, and ionization potentials are reported for one-(He + , H + 2 ), two-(H2, He), ten-(CH4) and 56-electron (C8H8) systems.

show abstract

Section: Discussionmentioning

confidence: 99%

Section: G Cubane (C8h8) Ionization Potentialmentioning

confidence: 99%

Section: G Cubane (C8h8) Ionization Potentialmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

An efficient basis set representation for calculating electrons in molecules

et al. 2016

View full text Add to dashboard Cite

show abstract

“…[34][35][36][37][38] Here, we will focus on the solvation contribution to the protonation equilibrium and reserve quantum mechanical intramolecular effects for subsequent treatment.…”

mentioning

confidence: 99%

Molecular Theories and Simulation of Ions and Polar Molecules in Water

1998

View full text Add to dashboard Cite

Recent developments in molecular theories and simulation of ions and polar molecules in water are reviewed. The hydration of imidazole and imidazolium solutes is used to exemplify the theoretical issues. The treatment of long-ranged electrostatic interactions in simulations is discussed extensively. It is argued that the Ewald approach is an easy way to get correct hydration free energies in the thermodynamic limit from molecular calculations; and that molecular simulations with Ewald interactions and periodic boundary conditions can also be more efficient than many common alternatives. The Ewald treatment permits a conclusive extrapolation to infinite system size. Accurate results for well-defined models have permitted careful testing of simple theories of electrostatic hydration free energies, such as dielectric continuum models. The picture that emerges from such testing is that the most prominent failings of the simplest theories are associated with solvent proton conformations that lead to non-gaussian fluctuations of electrostatic potentials. Thus, the most favorable cases for second-order perturbation theories are monoatomic positive ions. For polar and anionic solutes, continuum or gaussian theories are less accurate. The appreciation of the specific deficiencies of those simple models have led to new concepts, multistate gaussian and quasi-chemical theories, that address the cases for which the simpler theories fail. It is argued that, relative to direct dielectric continuum treatments, the quasi-chemical theories provide a better theoretical organization for the computational study of the electronic structure of solution species.2

show abstract

Coupled semiempirical molecular orbital and molecular mechanics model (QM/MM) for organic molecules in aqueous solution

Cummins

Gready

1997

J. Comput. Chem.

View full text Add to dashboard Cite

A coupled quantum mechanical and molecular mechanical (QM/MM) model based on the AM1, MNDO, and PM3 semiempirical molecular orbital methods and the TIP3P molecular mechanics model for liquid water is presented. The model was parameterized for each of the three molecular orbital methods using the aqueous solvation free energies of a wide range of neutral organic molecules, many of which are representative of amino acid side chains. The fit to the experimental solvation free energies was achieved by varying the radii in the van der Waals (vdW) terms for interactions between the solute, which was treated quantum mechanically, and the molecular mechanics (TIP3P) solvent molecules. It is assumed that the total free energy can be obtained as the sum of components derived from the electrostatic terms in the Hamiltonian plus a generally smaller “nonelectrostatic” term. The electrostatic contributions to the solvation free energies were computed using molecular dynamics (MD) simulation and thermodynamic integration techniques; the nonelectrostatic contributions were taken from the literature. It was found that the experimental free energies could be reproduced accurately (to within 1 kcal/mol) from the MD simulations, provided that the vdW parameter associated with hydrogen bonding (H bonding) was allowed to have different values depending on the QM method (AM1, MNDO, or PM3) and the type of functional group involved in the H bonding. Moreover, the radial distribution functions obtained from the MD simulations using such a parameterization scheme showed the expected H‐bonded structures between the solute and molecules of the solvent. The solvent‐induced dipole moments also compared favorably with the results of other QM/MM model calculations. © 1997 John Wiley & Sons, Inc. J Comput Chem 18: 1496–1512, 1997

show abstract

Progress toward chemical accuracy in the computer simulation of condensed phase reactions.

Abstract: We describe a procedure for the generation of chemically accurate computer-simulation models to study chemical reactions in the condensed phase. The

Cited by 96 publications

References 10 publications

An efficient basis set representation for calculating electrons in molecules

An efficient basis set representation for calculating electrons in molecules

Molecular Theories and Simulation of Ions and Polar Molecules in Water

Coupled semiempirical molecular orbital and molecular mechanics model (QM/MM) for organic molecules in aqueous solution

Contact Info

Product

Resources

About